The present invention relates to printers which are peripherals to computers and, more particularly, to printers adapted for use with silica-based print media.
Cellulose-based print media such as common paper, for example, have long been used as a media of choice for printing. Cellulose-based print media have qualities such as low cost, flexibility and low porosity, that make it amenable to generalized printing. In making identification cards though, other criteria become more desirable. These qualities include a high shear strength, an affinity to form mechanical and chemical bonds with toners and adhesives, and moisture resistance for example. These qualities are not strengths of cellulose-based print media, but are qualities of silica-based print media.
With the wide usage of cellulose-based print media there has evolve a variety of printers for use with computers which print images transmitted from the computer onto cellulose-based print media. A printer of this type generally includes at least a paper feeder to feed the cellulose-based print media into the printer, transfer system to apply the toner to the cellulose-based print media in a manner dictated by the image, and fixing system for securing the toner to the cellulose-based print media. These sub-systems perform their tasks in accordance with the print media under an assumption that the print media is cellulose-based, i.e., if the printer is not designed for use with plastic sheets then the plastic sheet may not feed, receive the toner or bond with the toner well.
Therefore, a problem with such printers is that they are restricted to use with such cellulose-based print media. Printing on the aforementioned silica-based print media on one of these commercially-available printers is then virtually impossible due to the characteristics of silica-based print media. For silica-based print media, these problems are primarily manifested in the fixing system. The fusing oil that is applied in a printer for cellulose-based print media applies a coat of oil on fusing rollers immediately prior to receipt of the cellulose-based print media and then withdraws. The silica-based print media is far more porous than cellulose-based print media and absorbs fusing oil much faster. Therefore, a fusing oil dispersing assembly designed for a cellulose-based print media disperses an amount of fusing oil inadequate for printing on a silica-based print media.
Further, fuser rollers in the fixing system have a heat differential that assists in bonding the toner to the cellulose-based print media. The heat in the fuser roller emanates from an internal heating element out through a liner on the fuser roller which is extremely smooth for a glossy finish on printed output. The heat differential brings with it an additional problem for silica-based print media. The heat differential is minimal for cellulose-based print media since the cellulose-based print media does not have a substantial tendency to adhere to the fuser rollers. Contrarily, silica-based print media adheres in the presence of heat and toner with its thermoplastic components augment this adhesion. Therefore, heating the silica-based print media in this way causes the silica-based print media to stick to the fuser rollers and curl around them, thus jamming the printer and ruining the printed output.
The liner on the fuser roller can also be problematic. With the increased porosity of the silica-based print media there is more air trapped in the media as it passes between the fuser rollers which are applying a substantial inward pressure. The liner having a slick, polished surface sticks to the silica-based print media due to vacuum, i.e., a suction-cup effect.
Accordingly, it is an object of this invention to adapt a commercially-available printer designed to print on cellulose-based print media to print on silica-based print media.
It is another object of this invention to provide additional fusing oil to a silica-based print media in a commercially available printer.
It is still another object of this invention to adjust the heat differential at the fuser rollers to decrease adhesion to a surface opposed to the toner in a silica-based print medium.
It is a further object of this invention to adapt the fuser roller liner on the fuser rollers such that they have additional release characteristics such that silica-based print media do not stick to the liner.
These and other objects of the invention will be obvious and appear hereinafter.